1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device including an edge type backlight unit.
2. Discussion of the Related Art
Generally, since LCD devices are driven with a low operating voltage, the LCD devices have low power consumption and are used as portable devices. Accordingly, the LCD devices are widely applied to various fields such as notebook computers, monitors, spacecrafts, airplanes, etc.
LCD devices include a lower substrate, an upper substrate, and a liquid crystal layer formed therebetween. In the LCD devices, the alignment of liquid crystal in the liquid crystal layer is adjusted with an electric field applied thereto, and thus, a light transmittance is adjusted, thereby displaying an image.
The LCD devices are non-emitting display devices that cannot self-emit light unlike other self-emitting flat panel display devices, and thus, a backlight unit is disposed as a light source in the rear of a liquid crystal panel. The backlight unit is largely categorized into a direct type and an edge type.
The direct type is a type in which lamps are disposed all over a bottom of the liquid crystal panel, and light emitted from the lamps is directly transferred to the liquid crystal panel. The edge type is a type in which the lamps are disposed at one side of the bottom of the liquid crystal panel, and light emitted from the lamps is transferred to the liquid crystal panel by a light guide plate.
Hereinafter, a related art LCD device including the edge type backlight unit will be described with reference to the drawing.
FIG. 1 is a cross-sectional view schematically illustrating a related art LCD device.
As seen in FIG. 1, the related art LCD device includes a backlight unit 1 and a liquid crystal panel 2.
The backlight unit 1 includes a light guide plate 10, a light source 20, an optical sheet 30, and a reflector 40.
The light guide plate 10 changes a traveling path of light emitted from the light source 20 in order for the light to be transferred to the liquid crystal panel 2. To change a traveling path of light in this way, a protrusion pattern 11 is formed at a bottom of the light guide plate 10. The protrusion pattern 11 is formed in a circular dot structure.
The light source 20 is disposed to face one side surface of the light guide plate 10. The light source 20 includes a light emitting diode (LED), a fluorescent lamp, or the like.
The optical sheet 30 allows light, passing through a top of the light guide plate 10, to be uniformly incident on the liquid crystal panel 2. The optical sheet 30 is configured with two prism sheets and one diffusive sheet.
The reflector 40 is disposed under the light guide plate 10, and reflects light passing through the bottom of the light guide plate 10, thereby allowing the light to be re-incident on the light guide plate 10.
The liquid crystal panel 2 includes a lower substrate 50, an upper substrate 60, and a liquid crystal layer (not shown) formed therebetween.
In the related art LCD device, light emitted from the light source 20 is reflected by the protrusion pattern 11 which is formed in the circular dot structure in the light guide plate 10, and thus, a traveling path of the light is changed toward the liquid crystal panel 2. However, in a case using the light guide plate 10 of the related art, an amount of light reflected by the circular dot structure is limited, and for this reason, there is a limitation in enhancing a light efficiency.